What is this plant and its characteristics?
bracken fern; Pteridium aquilinum
-triangular, erect fronds comprised of compound leaflets up to 5 feet in length
-dense patches from rhizome root
-widely dispersed throughout North America
-toxic fresh or dry
-highest toxicity in young, growing plants
What is the mechanism of toxicity for bracken fern?
*affects cattle, sheep, pigs, horses
*required prolonged ingestion; around 1 month
*ptaquiloside binds to and alkylates DNA, causing mutated codons associated with oncogenes
-able to be passed through milk; can cause cancer in humans
*thiaminase cleaves vitamin B1, resulting in thiamine deficiency and polioencephalomalacia
What are the clinical signs of thiamine deficiency due to bracken fern toxicity?
-in horses and pigs
-depressed mentation
-star gazing/opisthotonos
-blindness
-progression to cerebral edema and necrosis of neurons
What are the clinical signs of retinal degeneration due to bracken fern toxicity?
-seen in sheep consuming plant for multiple months
-causes blindness
What are the clinical signs of hemorrhagic syndrome due to bracken fern toxicity?
-seen in cattle; some signs similar in horses
-bone marrow aplasia
-thrombocytopenia
-GI tract ulceration
-urinary tract neoplasia
-death due to inability to clot
What are the locations for digestive tract cancer associated with bracken fern toxicity?
-esophageal
-stomach
How is bracken fern toxicity diagnosed?
-history of long-term ingestion
-hemorrhagic syndrome
-bone marrow depletion
-thrombocytopenia
-leukopenia
-blindness/signs of polio in horses
-bladder tumors
-disseminated hemorrhage of all organs post-mortem
What is the treatment for bracken fern toxicity?
-thiamine administration for thiamine deficiency
-no direct treatment for ptaquiloside
-antimicrobials for bone marrow suppression
-blood transfusion to replace clotting factors
What is the prevention for bracken fern toxicity?
-mowing
-digging out plant
-using herbicides
What is this plant and its characteristics?
perilla mint; Perilla frutescens
-strong mint smell
-erect square stems up to 2 to 3 feet tall
-broad, ovate leaves with acute tips and purple undersides
-tiny purple to white flowers on branch tips
-mostly in Southeast
-seeds and flowers more toxic than leaves
What is the mechanism of toxicity for perilla mint?
-primarily seen in cattle
-perilla ketones are readily absorbed from GI tract and exert toxic effects directly and after biotransformation
-ketones are severely toxic to endothelial cells and type 1 pneumocytes in lungs
-transformation of type 1 pneumocytes to type 2 pneumocytes which rapidly fill the lungs
-results in atypical interstitial pneumonia and emphysema
-resp. distress during exhalation
-pulmonary edema and secondary pleural effusion occur
What are the clinical signs of perilla mint toxicity?
*acute, atypical interstitial pneumonia:
-acute expiratory resp. distress
-rapid open mouth breathing
-“cow asthma”
How is perilla mint toxicity diagnosed?
*post-mortem:
-lungs fail to collapse
-lungs have “meaty” consistency
-glandular appearance to cut surface of lungs
-cuboidal cells instead of flat squamous epithelial cells lining the alveoli on histopath.
What is the treatment for perilla mint toxicity?
-no effective treatment once resp. signs begin
-avoid stress; can accelerate death
What is the prevention for perilla mint toxicity?
do not allow grazing of flowering mint
What is this plant and its characteristics?
cotton; Gossypium spp.
-shrubs that grow to 1 to 2 meters with broad, lobed leaves
-seeds in a capsule
-each seed/boll surrounded by fibers
-flowers are yellow to pink and give way to bolls
What is the mechanism of toxicity for cotton?
-seen in all animals; monogastrics > ruminants
-chronic toxicity from long-term ingestion
-gossypol is a polyphenolic pigment
-pigment is absorbed in GI tract and is highly protein bound to amino acids
-gossypol is cardiotoxic and causes congestive heart failure and dilated cardiac chambers
-results in pleural effusion and hepatic necrosis
Why are ruminants less susceptible to gossypol?
they can detoxify gossypol by forming stable complexes with proteins in the rumen
What are the clinical signs of cotton toxicity?
-sudden death due to cardiac failure
-congestive heart failure causing pleural effusion and hepatic necrosis
-labored breathing/dyspnea
-anorexia
-thin, potbelly appearance
-icterus
-red urine/hematuria
-poor performance
-weakness
How is cotton toxicity diagnosed?
-presumptive based on death of young animal eating cottonseed-containing rations for several weeks
-definitive by doing feed analysis for gossypol concentrations in conjunction with clinical signs
What is the treatment for cotton toxicity?
-no specific treatment
-avoid stress
-remove cotton products from diet
What is the prevention for cotton toxicity?
test gossypol levels in cottonseed products prior to feeding
